Steel Plate Weight Calculator: Formula, Density Table and Weight Chart
A steel plate weight calculator finds the mass of a plate by multiplying its area, thickness and material density, and the free tool below does this for rectangles, discs, rings and triangles in metric or imperial units. Use it alongside our pipe weight calculator and the other tools in the Fabrication & Calculators section.
Steel Plate Weight Calculator
Enter the plate details and select Calculate Plate Weight. Results appear here.
Step-by-step working
A steel plate weight calculator multiplies plate area, thickness and density: weight (kg) = length (mm) x width (mm) x thickness (mm) x density (kg/m3) / 1,000,000,000. For carbon steel at 7,850 kg/m3, each millimetre of thickness weighs 7.85 kg per square metre, so a 2,500 x 1,250 x 12 mm plate weighs about 294.4 kg.
This guide gives the plate weight formula in metric and imperial units, shape formulas for discs, rings, triangles and plates with holes, a density table for common metals and a weight chart by thickness. It is written for fabricators, estimators, planners and students who need a reliable theoretical weight before ordering, lifting or shipping plate.
Theoretical weight is a calculated value. Delivered weight differs slightly because of rolling tolerances, so use the method here for estimates and always confirm critical lifts against actual weights.
- Plate weight equals volume multiplied by density, which for a flat plate means area x thickness x density.
- Carbon steel plate weighs 7.85 kg per square metre for every millimetre of thickness, based on a density of 7,850 kg/m3.
- In imperial units, carbon steel plate weighs about 40.84 lb per square foot for every inch of thickness (0.2836 lb/in3).
- Stainless 304 is about 1.0% heavier and stainless 316 about 1.9% heavier than carbon steel, while aluminium 6061 weighs about one third as much.
- Holes and cutouts must be deducted as area before multiplying by thickness and density.
- Theoretical weight differs from delivered weight because plate is rolled within dimensional tolerances.
What Is Plate Weight?
Plate weight is the calculated mass of a flat metal plate, found by multiplying plate volume by the density of the material. In fabrication it is a theoretical value used for ordering, lifting and cost estimates, and delivered weight differs slightly because of mill tolerances.
The calculation works because a plate is a prism of constant thickness. The volume is simply the face area times the thickness, so any plate shape reduces to an area calculation. The density converts that volume to mass.
Strictly, mass is measured in kilograms or pounds-mass, while weight is the force in newtons. Fabrication and procurement use the word weight for mass, and this guide does the same.
How Do You Calculate Steel Plate Weight?
Steel plate weight is calculated as length x width x thickness x density, using consistent units. With dimensions in millimetres and density in kg/m3, divide the product by 1,000,000,000 to get kilograms.
What Is a Worked Example for a Rectangular Plate?
How Do You Calculate Plate Weight by Hand?
- Measure the plate. Record the length, width and thickness in millimetres, using the actual thickness if the plate is already cut.
- Find the area. Multiply length by width and divide by 1,000,000 to get square metres.
- Select the density. Use 7,850 kg/m3 for carbon steel, or the value for the actual material from the density table below.
- Calculate the unit weight. Multiply the thickness in millimetres by the density and divide by 1,000 to get kg/m2.
- Multiply by area. Multiply the unit weight by the area, and subtract the area of any holes before this step.
- Apply quantity and allowances. Multiply by the number of plates, and add any agreed trimming or tolerance allowance.
How Do You Calculate Discs, Rings, Triangles and Plates with Holes?
For shapes other than rectangles, replace the length x width term with the correct area formula, then multiply by thickness and density as before. Round holes are deducted as area before the volume is calculated.
Weld preparation and bevels remove very little metal and are normally ignored in plate weight estimates. Where you need the weld metal itself, see the consumable calculators described later in this guide.
Which Density Should You Use for Each Material?
Use 7,850 kg/m3 (7.85 g/cm3, 0.2836 lb/in3) for carbon and low-alloy steel plate, and a higher value for stainless steel and nickel alloys. The standard structural design value of 7,850 kg/m3 for steel is stated in EN 1993-1-1 (Eurocode 3: Design of steel structures), published by the European Committee for Standardization (CEN).
| Material | Density (kg/m3) | Density (g/cm3) | Density (lb/in3) | Weight versus carbon steel |
|---|---|---|---|---|
| Carbon / mild steel, low-alloy steel | 7,850 | 7.85 | 0.2836 | 1.000 |
| Stainless 304 / 304L | 7,930 | 7.93 | 0.2865 | 1.010 |
| Stainless 316 / 316L | 8,000 | 8.00 | 0.2890 | 1.019 |
| Duplex 2205 | 7,800 | 7.80 | 0.2818 | 0.994 |
| Aluminium 6061 | 2,700 | 2.70 | 0.0975 | 0.344 |
| Copper | 8,960 | 8.96 | 0.3237 | 1.141 |
| Brass (C26000) | 8,530 | 8.53 | 0.3082 | 1.087 |
| Titanium Grade 2 | 4,510 | 4.51 | 0.1629 | 0.575 |
| Nickel alloy 625 | 8,440 | 8.44 | 0.3049 | 1.075 |
These are typical handbook values, and the density of a specific heat can vary by a small fraction of a percent. If your project specification gives a density, use that figure through the custom density option. Our guide to duplex stainless steels explains why duplex grades sit slightly below austenitic stainless in density.
Plate specifications such as ASTM A36/A36M (carbon structural steel), ASTM A516/A516M (pressure vessel plates, carbon steel) and ASTM A240/A240M (stainless steel plate, sheet and strip) do not change the density used for weight estimates. Plate grades also carry base metal groupings for welding; see our P-Number and F-Number grouping guide.
Quick Reference: Steel Plate Weight per Square Metre and Square Foot
The charts below give theoretical weight per unit area for carbon steel plate, calculated at 7,850 kg/m3. Multiply the value by the plate area to get the plate weight, and use the table for 304 or 316 by applying the factors in Table 1.
| Thickness (mm) | Thickness (in) | Weight (kg/m2) | Weight (lb/ft2) | 1250 x 2500 mm plate (kg) |
|---|---|---|---|---|
| 3 | 0.118 | 23.55 | 4.82 | 73.59 |
| 4 | 0.157 | 31.40 | 6.43 | 98.12 |
| 5 | 0.197 | 39.25 | 8.04 | 122.66 |
| 6 | 0.236 | 47.10 | 9.65 | 147.19 |
| 8 | 0.315 | 62.80 | 12.86 | 196.25 |
| 10 | 0.394 | 78.50 | 16.08 | 245.31 |
| 12 | 0.472 | 94.20 | 19.29 | 294.37 |
| 16 | 0.630 | 125.60 | 25.72 | 392.50 |
| 20 | 0.787 | 157.00 | 32.16 | 490.62 |
| 25 | 0.984 | 196.25 | 40.20 | 613.28 |
| 32 | 1.260 | 251.20 | 51.45 | 785.00 |
| 40 | 1.575 | 314.00 | 64.31 | 981.25 |
| 50 | 1.969 | 392.50 | 80.39 | 1,226.56 |
| 60 | 2.362 | 471.00 | 96.47 | 1,471.88 |
| 80 | 3.150 | 628.00 | 128.62 | 1,962.50 |
| 100 | 3.937 | 785.00 | 160.78 | 2,453.12 |
| Thickness (in) | Thickness (mm) | Weight (lb/ft2) | Weight (kg/m2) | 4 ft x 8 ft plate (lb) |
|---|---|---|---|---|
| 3/16 | 4.8 | 7.66 | 37.39 | 245.03 |
| 1/4 | 6.3 | 10.21 | 49.85 | 326.71 |
| 5/16 | 7.9 | 12.76 | 62.31 | 408.38 |
| 3/8 | 9.5 | 15.31 | 74.77 | 490.06 |
| 1/2 | 12.7 | 20.42 | 99.70 | 653.41 |
| 5/8 | 15.9 | 25.52 | 124.62 | 816.77 |
| 3/4 | 19.0 | 30.63 | 149.54 | 980.12 |
| 1 | 25.4 | 40.84 | 199.39 | 1,306.83 |
| 1-1/4 | 31.8 | 51.05 | 249.24 | 1,633.54 |
| 1-1/2 | 38.1 | 61.26 | 299.09 | 1,960.24 |
| 2 | 50.8 | 81.68 | 398.78 | 2,613.66 |
Carbon steel plate weighs 7.85 kg/m2 per millimetre of thickness and 40.84 lb/ft2 per inch of thickness. A 10 mm plate therefore weighs 78.5 kg per square metre, and a 1/4 inch plate weighs about 10.21 lb per square foot.
How Accurate Is Theoretical Plate Weight?
Theoretical plate weight is accurate to the nominal dimensions and density used, but delivered plate is rolled within permitted thickness, width and length tolerances. The actual weight of a plate can therefore be above or below the calculated value by a small percentage.
Dimensional tolerances for rolled plate are set by general-requirement standards. Examples are ASTM A6/A6M (general requirements for rolled structural steel bars, plates, shapes and sheet piling) from ASTM International, EN 10029 (hot-rolled steel plates 3 mm thick or above: tolerances on dimensions, shape and mass) from CEN, and IS 2062 for structural steel from the Bureau of Indian Standards (BIS). Plates ordered to a nominal thickness are commonly supplied with a thickness tolerance, so purchasing rules for sold weight are agreed in the order.
- Pattern plate: chequered or floor plate carries raised pattern metal that flat-plate formulas do not include, so use the supplier’s published weight.
- Cut shapes: a laser or plasma cut part weighs less than the blank, so calculate the net area of the finished part.
- Coatings: galvanizing, paint and scale add a small amount that is usually ignored in estimates.
- Scale and trim: the calculator’s allowance field lets you add a percentage for trim or tolerance when your purchasing practice requires it.
Where Does Plate Weight Matter in Fabrication?
Plate weight drives purchasing, lifting, transport and equipment sizing in fabrication shops. It is used from the first estimate through to the lift plan, so an error carried through the job compounds at every stage.
- Estimating and ordering: material is bought by weight, so plate weight sets the cost and the number of sheets per tonne.
- Lifting and rigging: crane, clamp and sling selection starts from plate weight, and rigging gear weight is added to it.
- Transport: truck and container limits are set by gross load, so stacked plate weights add up quickly.
- Pressure vessels and tanks: shell courses, heads and nozzle reinforcement pads are cut from plate. For the formed ends, our hemispherical dish end weight calculator gives the head weight directly.
- Piping and skids: base plates, saddles and supports add to the pipe and fitting weight, which you can estimate with the elbow weight calculator and the pipe weight tool.
- Welding preparation: thick plate often needs preheat, and the carbon equivalent of the grade guides that decision. Use the carbon equivalent calculator to assess weldability.
How Does Plate Weight Relate to Weld Metal and Other Weights?
Plate weight covers the parent metal only and does not include weld metal, which is calculated separately from the joint geometry. Add weld metal weight to the plate weight when you need the finished assembly mass.
The amount of weld metal depends on the joint type, groove angle, root gap and length. The V-groove consumable calculator estimates the deposit for butt joints, and the fillet weld consumable calculation does the same for stiffeners and attachments. For the joint types themselves, see our guide to welding joint types.
The hub page for all weight and consumable tools is the fabrication calculation tools page, which groups each calculator by the stage of the fabrication workflow.
What Are the Common Mistakes and Limits?
Most plate weight errors come from mixing units or forgetting a deduction. The mistakes below are the ones that most often cause wrong orders and lift plans.
- Mixing units. Entering thickness in inches with density in kg/m3 gives a meaningless result. Use one unit system throughout.
- Using the steel density for other metals. Aluminium is about one third the weight of steel, so the wrong density changes the answer by a factor of about three.
- Forgetting holes and cutouts. Large openings and nozzle cutouts can remove a significant share of the blank.
- Confusing kg/m2 with kg/m. Plate uses weight per unit area, while bar and pipe use weight per unit length.
- Treating theoretical weight as sold weight. Mill tolerances and supplier practice mean delivered weight differs, so check the order terms.
- Ignoring rigging weight. A lift plan must include the weight of clamps, slings and spreader beams.
This tool and guide give theoretical weights from nominal dimensions and typical densities. Requirements for tolerances, material properties and lifting depend on the code edition, product standard and contract specification applicable to your project, so confirm critical values with the supplier and the responsible engineer.
Frequently Asked Questions
How do you calculate the weight of a steel plate?
Multiply the plate length, width, thickness and density using consistent units. With dimensions in millimetres and density in kg/m3, divide the result by 1,000,000,000 to get kilograms. For carbon steel, a shortcut is plate area in square metres times thickness in millimetres times 7.85. A 2,500 x 1,250 x 12 mm plate therefore weighs 3.125 x 12 x 7.85 = 294.4 kg.
What is the weight of a 10 mm steel plate per square metre?
A 10 mm carbon steel plate weighs 78.5 kg per square metre, found by multiplying 10 mm by 7.85 kg/m2 per millimetre. In imperial units this is about 16.1 lb per square foot. Multiply the figure by the plate area to get the weight of any size. A 1,250 x 2,500 mm sheet of this thickness weighs about 245.3 kg.
What density should I use for mild steel plate?
Use 7,850 kg/m3, which is 7.85 g/cm3 or 0.2836 lb/in3. This is the standard value for carbon and mild steel and for low-alloy steels such as Cr-Mo grades. It is also the structural steel value given in EN 1993-1-1. Use a custom density only when the project specification or material datasheet states a different figure.
Is stainless steel plate heavier than mild steel plate?
Yes, but only slightly. Stainless 304 at about 7,930 kg/m3 is roughly 1.0% heavier than carbon steel, and stainless 316 at about 8,000 kg/m3 is roughly 1.9% heavier. Duplex 2205 at about 7,800 kg/m3 is slightly lighter than carbon steel. Aluminium 6061 at about 2,700 kg/m3 weighs only about 34% as much as steel.
How do you calculate the weight of a plate with holes?
Calculate the net area first by subtracting the area of every hole from the plate area. The area of one round hole is pi/4 x d squared. Then multiply the net area by thickness and density. For a 500 x 300 x 10 mm carbon steel plate with four 20 mm holes, the net area is 148,743 mm2 and the plate weighs 11.68 kg.
What does a 4 ft x 8 ft x 1/4 inch steel plate weigh?
A 4 ft x 8 ft carbon steel plate that is 1/4 inch thick weighs about 326.7 lb, or 148.2 kg. The calculation is 48 in x 96 in x 0.25 in = 1,152 in3, multiplied by 0.2836 lb/in3. The same result follows from 32 ft2 x 10.21 lb/ft2. Real sheets vary slightly because of rolling tolerances.
Why does the delivered plate weight differ from the calculated weight?
The calculated value is theoretical, based on nominal dimensions and a standard density. Mills roll plate within thickness, width and length tolerances set by standards such as ASTM A6/A6M and EN 10029, so actual plates are slightly heavier or lighter. Trim, coatings and pattern metal on chequered plate also change the weight. Orders should state whether the price is based on theoretical or actual weight.
Key Terms
- Density
- The mass of a material per unit volume, for example 7,850 kg/m3 for carbon steel.
- Theoretical weight
- The weight calculated from nominal dimensions and density, before mill tolerances are considered.
- Unit weight
- The weight of plate per unit of area at a given thickness, expressed in kg/m2 or lb/ft2.
- Net area
- The face area of a plate after subtracting holes and cutouts.
- Annulus (ring)
- A circular plate with a concentric circular hole, such as a flange blank.
- Mild steel (MS)
- A low-carbon steel commonly supplied as structural plate, with a density of about 7,850 kg/m3.
- Mill tolerance
- The permitted variation in thickness, width and length of rolled plate set by the product standard.
Conclusion
A steel plate weight calculator needs only area, thickness and density, and for carbon steel the shortcut of 7.85 kg per square metre per millimetre covers most estimates. Use net area for plates with holes or cutouts, switch the density for stainless, aluminium or other alloys, and treat the result as a theoretical value that differs slightly from delivered weight. Always confirm critical lifts against actual weights and the order terms. As a next step, open the complete set of fabrication calculators to add pipe, elbow, dish end and consumable weights to your estimate.
This guide was prepared by the WeldFabWorld technical team from the standards listed in Standards and References. Verify every value against the code edition and specification applicable to your project.
Standards and References
- EN 1993-1-1, Eurocode 3: Design of steel structures, Part 1-1: General rules and rules for buildings, European Committee for Standardization (CEN)
- EN 10029, Hot-rolled steel plates 3 mm thick or above, Tolerances on dimensions, shape and mass, CEN
- ASTM International: ASTM A6/A6M, General Requirements for Rolled Structural Steel Bars, Plates, Shapes, and Sheet Piling
- ASTM A36/A36M, Carbon Structural Steel, ASTM International
- ASTM A240/A240M, Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications, ASTM International
- American Society of Mechanical Engineers (ASME): ASME BPVC Section II Part A, SA-516/SA-516M Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service
- Bureau of Indian Standards (BIS): IS 2062, Hot Rolled Medium and High Tensile Structural Steel